While carton opening or erecting devices are well known for use on carton carriers, and some of these include devices for squaring and retaining cartons thereon, none are known to disclose thin longitudinal guides located in predetermined positions on four sides thereof and which serve to square an already opened carton while it is being lifted, as from one conveyor to a second conveyor.
Adams U.S. Pat. No. 4,571,236 discloses leading and trailing carton transport lugs on a conveyor chain, wherein the leading lug extends across the width of one side of an open-ended carton lying on a second side, at the center thereof. The leading lug is inclined approximately 5.degree. rearwardly so as to engage the upper corner of the side to force the carton into a square attitude from a tendency toward a rhombic cross-sectional shape with the upper corner leading forward.
Taddei U.S. Pat. No. 3,888,164 discloses a conveying apparatus including two retaining members on separate chains serving to engage opposite sides of each container at opposite edges thereof after being removed from a magazine in a flat attitude by a suction cup.